1. Field of the Invention
The present invention relates to a liquid crystal display device. The invention more particularly relates to a liquid crystal display device configured to take a countermeasure against light spots attributable to shavings of an alignment film.
2. Description of the Related Art
Liquid crystal display devices include a TFT substrate having pixel electrodes, thin film transistors (TFT), etc. formed in a matrix; a counter substrate disposed in facing relation to the TFT substrate and having color filters, etc. formed at positions corresponding to the pixel electrodes of the TFT substrate; and liquid crystals put between the TFT substrate and the counter substrate. Images are formed by controlling the light transmittance of liquid crystal molecules of each pixel.
In a liquid crystal display device, an alignment film is formed at the boundary surface of the counter substrate and a liquid crystal layer of the TFT substrate and liquid crystal molecules are subjected to initial alignment by applying a rubbing process or an optical alignment process to the alignment film. Then, an amount of light transmitted through the liquid crystal layer is controlled by twisting or rotating the liquid crystal molecules from the initial alignment by an electric field.
On the other hand, for controlling the thickness of the liquid crystal layer, it is necessary to form a spacer between the counter substrate and the TFT substrate. While beads, etc. were conventionally dispersed as a spacer in the liquid crystal layer, columnar spacers have been formed on the counter substrate to control a gap between the TFT substrate and the counter substrate by the columnar spacers in recent years in order to control the gap (liquid crystal layer) more exactly.
On the other hand, an additional problem occurs by using the columnar spacer. For example, JP-A-2005-242297 describes that a frictional force is decreased when the columnar spacer is displaced in a case of pressing the counter substrate from the outside so that the columnar spacer can easily return to the initial place when the external pressure is removed. For this purpose, JP-A-2005-242297 discloses that a pedestal having an area smaller than that at the top end of the columnar spacer is formed as a pedestal which is formed on the TFT substrate.
Further, a problem of generating shavings of the alignment film also occurs when the columnar spacer displaces laterally. Other documents concerning scraping of the alignment film or columnar spacers include JP-A-2007-328247, JP-A-2008-170690, JP-A-2009-58618, JP-A-2009-282262, JP-A-2010-8616, and JP-A-Hei 5-107545. It is to be noted that JP-A-2005-242297 corresponds to U.S. Pat. No. 7,502,090, JP-A-2009-58618 corresponds to USP 2009/0059155, and JP-A-2009-282262 corresponds to USP 2011/0080548.